Recently, expectations for a solar cell capable of directly converting solar energy into electric energy have increased rapidly as an energy source of the next generation, in particular, from a viewpoint of global environmental problems. As the solar cell, various solar cells such as a solar cell using a compound semiconductor or an organic material are included, and currently, a solar cell using silicon crystal is mainly being used.
Then, currently, a solar cell which has been manufactured and sold most commonly is a solar cell having a structure where electrodes are respectively formed on a light receiving surface on a side on which solar light is incident and on a back surface on an opposite side of the light receiving surface. However, when the electrode is formed on the light receiving surface, the amount of solar light to be incident is decreased by the area of the electrode due to reflection and absorption of the solar light in the electrode.
Therefore, for example, as disclosed in Japanese Unexamined Patent Application Publication No. 2005-101151 (PTL 1), a solar cell (a hetero-junction back contact cell) in which an i-type amorphous silicon film is formed on a back surface of an n-type single crystal silicon substrate, an n-type amorphous silicon film and a p-type amorphous silicon film are formed thereon, and an electrode is formed thereon has been developed.